How to compose modules containing method_missing in ruby

Question

I have a couple of modules that extend method missing:

module SaysHello
    def respond_to?(method)
        super.respond_to?(method) || !!(method.to_s =~ /^hello/)
    end
    def method_missing(method, *args, &block)
        if (method.to_s =~ /^hello/)
            puts "Hello, #{method}"
        else
            super.method_missing(method, *args, &block)
        end
    end
end

module SaysGoodbye
    def respond_to?(method)
        super.respond_to?(method) || !!(method.to_s =~ /^goodbye/)
    end
    def method_missing(method, *args, &block)
        if (method.to_s =~ /^goodbye/)
            puts "Goodbye, #{method}"
        else
            super.method_missing(method, *args, &block)
        end
    end
end

class ObjectA
    include SaysHello
end

class ObjectB
    include SaysGoodbye
end

This all works well, eg ObjectA.new.hello_there outputs "Hello, hello_there". Likewise, ObjectB.new.goodbye_xxx outputs "Goodbye, xxx". respond_to? also works, eg ObjectA.new.respond_to? :hello_there return true.

However, this doesn't work very well when you want to use both SaysHello and SaysGoodbye:

class ObjectC
    include SaysHello
    include SaysGoodbye
end

While ObjectC.new.goodbye_aaa works correctly, ObjectC.new.hello_a acts strange:

> ObjectC.new.hello_aaa
Hello, hello_aaa
NoMethodError: private method `method_missing' called for nil:NilClass
    from test.rb:22:in `method_missing' (line 22 was the super.method_missing line in the SaysGoodbye module)

It outputs correctly, then throws an error. Also respond_to? doesn't correctly, ObjectC.new.respond_to? :hello_a returns false.

Finally, adding this class:

class ObjectD
    include SaysHello
    include SaysGoodbye

    def respond_to?(method)
        super.respond_to?(method) || !!(method.to_s =~ /^lol/)
    end


    def method_missing(method, *args, &block)
        if (method.to_s =~ /^lol/)
            puts "Haha, #{method}"
        else
            super.method_missing(method, *args, &block)
        end
    end
end

Also acts strangely. ObjectD.new.lol_zzz works, however ObjectD.new.hello_aand ObjectD.new.goodbye_t both throw a name exception after outputting the correct string. respond_to? also fails for hello and goodbye methods.

Is there a way to get this all working correctly? An explanation of how method_missing, Modules and super are interacting would also be really useful.

EDIT: coreyward solved the problem, if I use super instead of super.(args...) in all the methods I define, the program works correctly. I don't understand why this is though, so I asked another question about this at What does super. do in ruby?

How to compose modules containing method_missing in ruby

2 Answers